Such inserts may comparatively readily be fixed permanently by moulding-in or permanent bonding, but when there is a requirement for removability or replacability problems arise in achieving a fixing which is at the same time fluid-proof and secure.
Such fixings have commonly been achieved by the use of spring clips or Jubilee Clip type devices both of which are broken rings of which the ends are drawn together--in the one case by the resilience of the ring material itself and in the other case by a screw linkage joining them. In both cases there is an area of flexible material which is underlying the broken part of the ring where a seal is not assured and in the case of the Jubilee Clip the tightening of the screw can cause distortion and creep of the flexible material underneath the clip as a result of the pressures applied.